Finite element modelling and characterization of 3D cellular microstructures for the design of a cementless biomimetic porous hip stem

Publication date: 5 July 2018
Source:Materials & Design, Volume 149
Author(s): Hassan Mehboob, Faris Tarlochan, Ali Mehboob, Seung-Hwan Chang
Titanium porous cellular microstructures are commonly used in bone mimetic implants. The orientations of the internal strut architectures of these microstructures affect the mechanical performance under various loads; however, poor architectural designs may result in their failure. Three-dimensional (3D) finite element models of cubic, diamond, and body-centered cubic (BCC) geometries were constructed with 1–4 numbers of unit cells and 4–10-mm unit cell size. Mechanical testing of the finite models of the cubic, diamond, and BCC structures with porosities of 20–90% was performed under compression, bending, and torsional loads. The BCC structure showed moderate and relatively isotropic mechanical properties compared with those of the diamond and cubic structures. A design space for a BCC porous structure with a porosity of 40–65% was estimated to model a complete porous stem to mimic the bone properties. Furthermore, the stems with the determined porous mechanical properties of the BCC microstructures with 20–90% porosities were tested under physiological loading conditions. It was found that a porosity of 47.3% of the BCC structure exhibits the closest stiffness (469N/mm) to an intact bone (422N/mm). This was predicted by our suggested design space of the porosity.

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